CVE-2021-21328
5.3 · MEDIUMOverview
CVE-2021-21328 is a medium-severity vulnerability affecting vapor_project vapor. It was published on February 26, 2021 and has a CVSS 3.1 base score of 5.3 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
Vapor is a web framework for Swift. In Vapor before version 4.40.1, there is a DoS attack against anyone who Bootstraps a metrics backend for their Vapor app. The following is the attack vector: 1. send unlimited requests against a vapor instance with different paths. this will create unlimited counters and timers, which will eventually drain the system. 2. downstream services might suffer from this attack as well by being spammed with error paths. This has been patched in 4.40.1. The `DefaultResponder` will rewrite any undefined route paths for to `vapor_route_undefined` to avoid unlimited counters.
Remediation
Check the references section for vendor advisories and patches from vapor_project. Update vapor to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| vapor_project | vapor | >= 0, < 4.40.1 | Affected |
References
Frequently Asked Questions
What is CVE-2021-21328?
CVE-2021-21328 is a medium-severity vulnerability affecting vapor_project vapor. It was published on February 26, 2021 and has a CVSS 3.1 base score of 5.3 (MEDIUM).
How severe is CVE-2021-21328?
This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-21328?
Check the references section for vendor advisories and patches from vapor_project. Update vapor to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-21328?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-21328 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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